Combination expansion device and ullage rod



Oct. 12, 1954 E, FLETCHER 2,691,462

COMBINATION EXPANSION DEVICE AND ULLAGE ROD Filed Aug. 31, 1953 i Z m 2 57 IN V EN TOR.

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Patented Oct. 12, 1954 COMBINATION EXPANSION DEVICE AND ULLAGE ROD Edward H. Fletcher, Cedar Falls, Iowa, assignor to Deere Manufacturing 00., Dubuque, Iowa, a

corporation of Iowa Application August 31, 1953, Serial No. 377,290

4 Claims. (01. 22085) This invention relates to a new and. useful means of measuring the level of liquid in a container, such means also serving as an expansion device to compensate for pressure and volumetric changes of the fluids in said container. More particularly this invention relates to the above as regards the fluid reservoir of hydraulic power units on a tractor.

The best known and most common means of measuring liquid in a container is by the dip stick or ullage rod method. This consists basically of a metal rod with suitable markings, extending through an orifice at the top of the container. The level of the liquid is recorded on the rod. and readings are taken when the rod is removed from the container. The fault with this method is that normally the rod fits loosely through the orifice and insufficient protection is given to prevent moisture and foreign matter from entering the hydraulic system. Unless suflicient filtering and/or periodic replacement of the fluid occurs an eventual breakdown of the hydraulic system will result.

It is also know to those familiar with the art that hydraulic systems, particularly those subject to temperature variations, should not be enclosed in rigid containers. In such systems, when the liquid expands or contracts due to such temperature changes, abnormal pressures are applied to the container walls, often resulting in breakdown of the containers weaker members such as at its gaskets, seals, packing, etc. Venting the system directly to the atmosphere to prevent the pressure variations causes the introduction of moisture and other foreign matter to the hydraulic system.

It is the object of this invention to provide a means of measuring the liquid in the hydraulic system while retaining a closed system and also by this same device to introduce into the hydraulic system a means of maintaining atmospheric pressure within the hydraulic reservoir without venting directly from the reservoir to the atmosphere. By use of my invention as described herein, the hydraulic fluid remains in a completely enclosed but non-rigid container.

Fig. 1 is a side elevational view of the tractor with the forward portions being cut away and shown in section to reveal the details of the power steering unit.

Fig. 2 is a fragmentary enlarged plan View as seen along the line 2-2 of Fig. 1.

Fig. 3 is a partial section as seen along the line 38 of Fig. 2.

Fig. 4. is a detailed side elevation, partly in section, of the flexible tubular ullage rod assembly shown in section.

Fig. 5 is .a view, similar to Fig. 4, of a variation of a flexible ullage rod assembly.

The tractor is similar in appearance to presently known commercial line tractors. An internal combustion engine 8, covered by a hood ill, and a transmission 9 is supported by a frame H which in turn receives support from a rear axle i2 and rear traction wheels 13. The forward section of the tractor is carried by steerable front wheels I4 controlled through a hy draulic power steering system, that includes a steering shaft l6, steerin wheel i7 and front wheel spindle 20. A grille IQ of not unconventional design is at the front of the tractor.

Included in the hydraulic power steering system is a spindle pedestal 2| serving also as a fluid reservoir for hydraulic liquid at a predetermined level 24. Extending upright and through the bottom of the pedestal is a spindle shaft 25. A conventionalseal 2%; is placed about the shaft 25 at the base.

Cut in the top wall of the pedestal is a cylindrical opening 21 with threaded walls 28. Extending vertically downward through the openin 21 is a combined closure expansion and ullage assembly or device I8, see Fig. 4, comprising a cylindrical plug or closure or mounting me1nber 29 exteriorly threaded at 36 to fit the threads 28 of the opening 2'1. A screw driver slot 3| is cut diametrically across the plug. A vent 32 is drilled vertically through the plug.

An under portion 33 of the plug 29 is reduced in diameter and has a recess or groove 34 extending circumferentially about said under portion 33.

Extendin over the under portion 33 of the .plug 29 is an imperforate hollow flexible member such as a rubber tube 35 closed at its lower end 31.

The tube 35 is sealed to the plug 29 by means of a wire clamp 36, which compresses the upper section of the rubber tube 35 in the recess 34 of the under section of the plug 29. The lower end 31 of the tube 35 normally depends past the fluid level 24 to provide means serving as an ullage element.

Referring to Fig. 5: The rubber flexible tubular member 35a is of such length that its lower portion 31a does not depend into the hydraulic liquid, but extending vertically downward from the lower portion 31a of the tubular member 3511 is a rod 38 made of solid rubber or other suitable material, which depends into the hydraulic liquid to perform the ullage function.

As is, I believe, obvious, the hydraulic fluid readings are taken by removing the assembly W as a unit from :the opening 21 in the top wall of the reservoir by unscrewing the assembly, with a screw driver or other suitable means, and observing the fluid level mark on the outer surface of the assembly. Assuming the threaded joint holding the plug in the top wall of the reservoir to be a erfect seal, it becomes evident that other than at the time of readings the hydraulic system remains in a closed container.

As the hydraulic system undergoes temperature variations, corresponding volumetric changes of the liquid and gases are generated within the hydraulic system. The tubular ullage rod assembly and more particularly the flexible rubber tubular member of the assembly, being by nature of a collapsible and expandable substance, provides a collapsible and expansible chamber and adjusts itself to the volumetric change within the closed hydraulic system; and this chamber, being vented directly to the outer air by means of the vertically drilled hole in the plug, remains at atmospheric pressure. Assuming the pressure effect of the rubber tube itself to be negligible, the atmospheric pressure is transferred through the walls of the tube to the reservoir. Thus, regardless of temperature variations and corresponding volumetric changes of the fluids in the hydraulic system, the pressure within the fluid reservoir remains atmospheric. Also the system remains completely sealed off from outside moisture and foreign matter.

The above detailed description of my invention consists of only two of .several variations of such invention. Other variations should be readily ascertainable by those familiar with the art. It should be therefor understood that the description is not intended to narrow or limit my invention.

I claim:

1. In a container adapted to contain fluid at a predetermined level and including imperforate walls except for a top wall portion in which is formed an opening for access to the interior of the container, a combined closure, expansionaccommodating and ullagedevice comprising: a closure member removably fitting the opening to provide a fluid-tight and dirt-proof seal, said member, when in place, having an under portion exposed to the interior of the container and of reduced size relative to the opening; a tubular member of flexible material impervious to fluid in the container and having upper and lower ends, said upper end being open and permanently joined to the reduced under portion of the closure member to provide an air-tight and dirt-proof seal, said tubular member depending into the container and said lower end being closed so that said tubular member forms a collapsible chamber within the container, said closure member having an aperture therethrough to vent said chamber to atmosphere; and said tubular member being of sufficient length .to dependintothe fluid in the container to serve'as an ullage element, said tubular member throughout its length having a cross-sectional size smaller than the container opening so as to permit withdrawal thereof from the container when the closure member is removed.

2. In a container adapted to contain fluid at a predetermined level and including imperforate walls except for a top wall portion in which is formed an opening for access to the interior of the container, a combined closure, expansionaccommodating and ullage device comprising: an apertured mounting member removably fitting the opening to provide a fluid-tight and dirtproof seal around its edges, said member, when in place, having an under portion exposed to the interior of the container; a tubular member of flexible material impervious to fluid in the container and having upper and lower ends, said upper end being open and permanently joined to the under portion of the mounting member around the aperture to provide an air-tight and dirt-proof separation between said aperture and the container while leaving the aperture open to atmosphere, said tubular member depending into the container and said lower end being closed so that said tubular member forms a collapsible chamber within the container but exposed to atmosphere via the aperture in the mounting member; and said tubular member being of sufficient length to depend into the fluid in the container to serve as an ullage element, said tubular member throughout its length having a crosssectional size smaller than the container opening so as topermit withdrawal thereof from the container when the closure member is removed.

3.,'In a container adapted to contain fluid at a predetermined level and including imperforate walls except for a top wall portion in which is formed an opening for access to the interior of the container, 2. combined closure, expansionaccommodating and ullage device comprising: a closure member removably fitting the opening to provide a fluid-tight and dirt-proof seal, said member, when in place, having an under portion-exposed to the interior of the container; a hollow member of flexible material impervious to fluid in the container and having an upper open end permanently joined to the under portion of the closure member to provide an airtight and dirt-proof seal, said hollow member depending into the container and having a closed lower end so that said hollow member forms a collapsible chamber within the container, said closure member having an aperture therethrough to vent said chamber to atmosphere; and said hollow member having means thereon of sufflcient length to depend into the fluid in the container to serve as an ullage element, said hollow member and said ullage element each having a cross-sectional size smaller than the container opening so as to permit withdrawal thereof from the container when the closure member is removed.

4i. In a container adapted to contain fluid at a predetermined level and including imperforate walls except for a top wall portion in which is formed an opening for access to the interior of the container, .a combined closure, expansionaccommodating and ullage device comprising: an .apertured mounting member removably fitting the opening to provide a fluid-tight and dirtproof seal around its edges, said member, when in place, having an under portion exposed to the interior of the; container; a hollow member of flexible material impervious to fluidin the container and having upper and lower ends, said upper end being open and permanently joined to the under portion of the mounting member around the aperture to provide an airtight and. dirt-proof separation between said aperture and the container while leaving the aperture open to atmosphere, said hollow member depending into the container and said lower end being closed so that said tubular member forms a collapsible chamber within the container 10 but exposed to atmosphere via the aperture in the mounting member; and said hollow member having means thereon of sufficient length to depend into the fluid in the container to serve as an ullage element, said hollow member and 5 when the closure member is removed.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,867,204 Bohnhardt July 12, 1932 2,405,614 Shriro Aug. 13, 1946 2,647,657 Krupp Aug. 4, 1953 

